<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>控制样式</title>


    <style>
        .d1{
            border: 1px solid red;
            width: 100px;
            height: 100px;
        }

        .d2{
            border: 1px solid blue;
            width: 200px;
            height: 200px;
        }


    </style>
</head>
<body>

    <div id="div1">
        div1
    </div>

    <div id="div2">
        div2
    </div>


<script>
    var div1 = document.getElementById("div1");
    div1.onclick = function(){
        //修改样式方式1
        div1.style.border = "1px solid red";

        div1.style.width = "200px";

        //font-size--> fontSize
        div1.style.fontSize = "20px";

    }


    var div2 = document.getElementById("div2");
    div2.onclick = function(){
        div2.className = "d1";
    }


</script>

</body>
</html>